In U.S. Pat. No. 5,108,780 a single fibre of reinforcing filament is irradiated with a plasma in a vacuum chamber prior to being coated with a thermoplastic coating. Immediate coating of the plasma treated fibre with the thermoplastic produces stronger interfacial shear strength than when the fibre is exposed to air or other free-radical-quenching species before it is coated.
The abstract of JP2005171432 describes a method of manufacturing fibres for polymer composite reinforcement. The fibres are subjected to a first plasma treatment under ordinary pressure followed by a second plasma treatment in a medium containing a gaseous alkene or alkyne at ordinary pressure. An adhesive is imparted after the plasma treatments.